Extended-range spectroscope for intense radiation sources

ABSTRACT

An improved spectroscope for securing simultaneous data regarding both spatial and spectral information from intense sources of radiation. A dual-mode optical system is utilized wherein spatial information is directed to three adjacent screens for the near ultraviolet, visible, and near infrared, respectively, and spectral information is directed to an elongated spectra screen located directly below the three spatial screens. This dual-mode function is performed through the use of fluorescent material technology which replaces the more conventional and complex image tube and detector array technology, thereby resulting in a truly portable spectroscope which is light weight, compact, low cost, requires little maintenance, and has very low power requirements.

Poulsen 51% Dec. 11, 1973 EXTENDED-RANGE SPECTROSCOPE FOR INTENSERADIATION SOURCES [75] Inventor: Peter D. Roulsen, San Diego, Calif.

[73] Assignee: General Dynamics Corporation, San

Diego, Calif.

221 Filed: o:.12,1971

211 Appl.No.: 188,270

[52] US. Cl 356/51, 250/83 R, 356/74 [51] Int. Cl. G013 3/00 [58] Fieldof Search 356774, 76-79, 356/83, 84, 98, 51; 250/833 H, 83.3 HP, 83.3UV, 83 R [56] References Cited UNITED STATES PATENTS 2,444,560 7/1948Feldt et a1 356/83 3,260,180 7/1966 Teeple 356/79 UX 3,363,525 [/1968Teeple 356/79 X 3,379,830 4/1968 Menke 250/833 H 3,580,679 5/1971 Perkin356/76 FOREIGN PATENTS OR APPLICATIONS 15,493 8/1901 Great Britain.;356/98 OTHER PUBLICATIONS Low: Observing Plans for Octobers Eclipse 11Sky and Telescope, Vol. 17, No. 9, July 1958, pages 450-453.

Harwit: spectrometric lmager, Applied Optics, Vol. 10, No.6, June 1971,pages 1415-1421.

Primary Examiner-Ronald L. Wibert Assistant Examiner-F. L. EvansAtt0rneyJohn R. Duncan et al.

[57] ABSTRACT An improved spectroscope for securing simultaneous dataregarding both spatial and spectral information from intense sources ofradiation. A dual-mode optical system is utilized wherein spatialinformation is directed to three adjacent screens for the nearultraviolet, visible, and near infrared, respectively, and spectralinformation is directed to an elongated spectra screen located directlybelow the three spatial screens. This dual-mode function is performedthrough the use of fluorescent material technology which replaces themore conventional and complex image tube and detector array technology,thereby resulting in a truly portable spectroscope which is lightweight, compact, low cost, requires little maintenance, and has very lowpower requirements.

22 Claims, 4 Drawing Figures 0.3 MICRON |.1 MICRONS SHEEI 1 BF 3 L7MICRONS 0.3 MICRON FIG.|

EXTENDED-RANGE SPECTROSCOPE FOR INTENSE RADIATION SOURCES BACKGROUND OFTHE INVENTION The invention relates to a spectroscope for analysis ofintense sources of ultraviolet, visible, and infrared radiation, andmore particularly to a system which provides for alignment of thespectroscope with the source by viewing the source on an imaging screenby means of a dual-mode optical system.

Electromagnetic radiation in the wavelength range of 3,800 to 7,800angstrons (A) is generally considered as visible to the human eye. Theultraviolet range begins at the short wavelength limit of visibilitywhich appears violet (4,000A) to the human eye and extends to thewavelengths of x-rays (less than 1,000A). The ultraviolet range isfurther subdivided into the near (4,000-3,0- A), far (3,000-2,000), andextreme (below 2,000A) ultraviolet regions. The extreme ultravioletrange is sometimes called the vacuum ultraviolet because the absorptionby air of these wavelengths requires an evacuated volume to transmit theradiation. At the long wavelength limit of visibility, which appears red(8,000A or 0.8 micron), begins the infrared range which extends to thewavelengths of microwave (greater than 1,000 microns). The near infraredrange is generally considered to be from 0.8 to 2.5 microns.

Ultraviolet energy in the near region is sometimes called black lightand is used to excite fluorescent pigments in dyes and inks to producedramatic effects in decorations and advertising as well as practicalutility in automotive and aircraft instruments and invisibleidentification such as laundry marks. Likewise, the invisible infraredradiation has many scientific, industrial, and military applicationsincluding chemical analysis and spectroscopy, industrial processcontrols, invisible signaling, burglar alarms, detection of militarytargets, and spacecraft guidance.

Detection of these invisible radiation sources must first beaccomplished before a spectroscope can be properly aimed or aligned withthe source for analysis or interrogation of the radiation energy.Detectors of ultraviolet radiation include phototubes, photovoltaic orphotoconductive cells, and other radiometric devices. Infrared detectorsinclude thermal detectors, which use a change in electrical resistanceor other physical changes caused by a temperature increase of thedetecting element when radiated with infrared energy, photovoltaic andphotoconductive cells, and other radiometric devices. Whatever detectorsare employed, they all essentially convert the radiant energy into anelectrical signal which is amplified electronically and sent to sometype of display which can be read by an operator. Displays includedigital readouts, analogue dials, lights, or cathode ray tubes.

Once a radiation source is detected, the spectroscope is aimed at thesource. This may be accomplished by aiming the spectroscope at the sameordinates, conventionally azimuth and elevation, as the detector, or thedetecting device may be attached to and boresighted" with thespectroscope so that both are simultaneously aiming at the light source.

lt is usually desirable to have a spatial display for the operator alongwith the source detection displays. The simplest of display would be asight ring. Another technique would utilize conventional optics in theform of a telescope. There are currently systems available which utilizea conventional T.V. camera and display for detecting the visual range ofradiation and for the spatial display. Electronically coupled to theT.V. display are the ultraviolet and infrared detector circuits in sucha way that any radiation source in these ranges are projected onto theT.V. display, appearing as a visible light, to give a spatial readout ofthe source location.

Such systems are cumbersome, requiring electrical power sources andhaving electronic components and circuitry which require periodicadjustment and maintenance, and do not have the degree of portabilityrequired for quick field usage. Additionally, thereare the problems ofparallax between the several detection systems, the spatial display, andthe spectroscope, and the need for periodic boresighting and adjustingof these systems.

Thus, there is a need for an improved device for detecting and spatiallyorienting a radiation source for spectral analysis, wherein the deviceutilizes no electronic circuitry, and is sufficiently small andlightweight to be hand held by an operator.

SUMMARY OFTHE INVENTION It is, therefore, an object of this invention toprovide an improved spectroscope overcoming the above noted problems.

A further object of this invention is to provide a spectroscope devicewhich will simultaneously provide spatial information on ultraviolet,visible, and infrared wavelength regions and whenever the devide isaimed at a high intensity source to additionally provide a spectraldisplay of the radiation source.

Another object of this invention is to detect and analyze intenseradiation sources without the use of complex image tube and electronicdetector devices.

Another object of this invention is to provide an extended rangespectroscope for intense radiation sources which is sufficiently compactto permit handheld operation.

Another object of this invention is to provide an extended rangespectroscope which is self-contained within a single package thatrequires no outside source of electrical power.

Another object of this invention is to-provide an extended rangespectroscope which eliminates the problems of parallax and alignmentbetween the visual detector and the spectral detector.

The above objects, and others, are accomplished by the present inventionutilizing a new and novel dualmode optical system, which collects theincoming radiation and directs the energy to a spatial display, and whenthe device is centered on the high intensity radiation source the energyis diverted to the spectral optic system while maintaining thesurrounding spatial information on the spatial display.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages of the presentinvention reside in the construction and cooperation of elements ashereinafter described, reference being made to the accompanying drawingswhich show a preferred embodiment of the invention, and forming a parthereof, wherein:

FIG. 1 is a view of the spectroscope screens as seen by the operatorlooking through the eyepiece.

FIG. 2 is a plan-view schematic of the image optics of the spectroscope.

FIG. 3 is a plan-view schematic of the spectral optics of thespectroscope.

FIG. 4 is a side-view schematic of the combined image and spectraloptics of the spectroscope.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings indetail, FIG. 1 is a view of the various screens as seen by the operatorwhen looking through the eyepiece. The spatial screen assembly 10,comprises three screens each having the same field of view, and eachhaving an opaque spot 12, located near their respective centers. Eachscreen provides spatial information for a different spectral region, theleft screen showing ultraviolet, the center screen showing visible, andthe right screen showing nearinfrared, thereby yielding spatial displaythroughout the region of 0.3 to 1.7 microns. While the opaque spot 12 isillustrated as being located near the respective centers of the screens,it is not limited to this location and may be offset in any desireddirection on the screens. The expected source of radiation is kept inthe spatial screens by the operator, or the operator moves the hand-heldspectroscope much like panning a camera until the source is observed.When a bright source is noted on any of the three screens, thespectroscope is moved to position the opaque spot over it. When sopositioned, the source radiation will be diverted to the elongatedspectral screen 11, which has an associated wavelength scale along thebottom edge. Bright spots or continua will appear at positionscorresponding to the radiation wavelengths. The spatial location of thesource of radiation can then be noted by the position of the opaque spoton the image screens, while the source spectroscopic data can be notedon the spectral screen 11.

FIG. 2 is a plan-view schematic presentation of the image optics of thespectroscope, wherein the previously described spatial screen assembly10, is viewed on edge near the bottom of the view. Spectral screen 11,is likewise on edge in conformity with screen assembly 10, and out'ofview'below screen 10. The optical train can generally be divided intothe controlling optics 1, and the imaging optics 2. Incoming light iscollected by the primary objective mirror 14 which is a front-surface,converging mirror. It should be noted that for convenience radiations inthe near ultraviolet, visible, and near infrared ranges will hereinafterbe generally described as light. The secondary objective mirror 16 is afront-surface diverging mirror. The col lecting optics can be focusedfor targets at various distances by moving the secondary objectivemirror 16 to change its distance from the primary objective mirror 14.This mirror combination focuses the incoming light to a planeimmediately in front of the secondary objective lens 18, as shown inFIG. 2 by a dotted line through point 31. The utilization of mirrors 14and 16 prevents chromatic aberration and ultraviolet absorption thatwould exist if lenses were utilized for the collecting optics, andadditionally mirrors are preferred because they are light weight andprovide wide aperture.

Two 45 front surface mirrors l9 and 21 are disposed into the light pathpassing through the secondary objective lens 18. Another set of frontsurface mirrors 20 and 22 are so located to relay light to theirrespective image-forming lenses 23 and 27. Light passing through thesecondary objective lens is also relayed to the larger image-forminglens 25. Thus it can be seen that the incoming light collected by theprimary objective mirror 14 is divided and relayed to the threeimage-forming lenses 23, 25 and 27, the degree of division of thecollected light between the three paths being a function of the depthsinto the light path which the 45-degree front surface mirrors 19 and 21are disposed.

Immediately behind image-forming lens 23, is an ultraviolet pass-filter24, which limits light transmission theret'hrough to the ultravioletregion. In a like manner, infrared pass-filter 28 is located immediatelybehind image-forming lens 27 and limits light transmission to thenear-infrared region. Visible pass-filter 26 is located behind lens 25,and in a like manner limits the light transmission to the visible range,thereby giving a spatial presentation of better quality than thatobservable by the unaided eye, much like a pair of optically correctsunglasses improves observations.

As previously described, spatial screen assembly 10 comprises threeseparate screens, which are viewable through the eyepiece 30. The centerscreen may be ground (frosted) glass located at the focal plane todisplay the visible region image. Sensing can be accomplished simplywith the human eye, and use of a ground glass screen is usually thepreferred embodiment, however in some instances where improvedsensitivity and resolution are required in visible observation, theground glass screen is eliminated, allowing the focused image to berelayed directly by the eyepiece 30. This eliminates light loss due toscattering away from the eyepiece, and does away with resolutionlimitations imposed by the ground glass. In this case however, theeffective aperture of the human eye, even when looking through variousconfigured eyepieces, is such that a hole in the field of vision isapparent due to the center hole in the primary objective mirror 14. Thisrequires off-axis operation to overcome the problem, and is thereforenot considered to be the preferred embodiment, although it should beappreciated that for special circumstances it may be desirable andfeasible to so arrange the optics. It should also be appreciated thatthe three spatial screens of assembly 10 may be of equal size or ofvarious sizes as for example in FIG. 2 the center visible screen and itsassociated optics are illustrated as larger than the left and rightscreens. In other applications it may only be necessary to have one ortwo spatial screens if the range of wavelengths of interest issufficiently small. As an example it may only be necessary to havevisual range screen, or a visual and an infrared set of screens forviewing molten metal in a foundary or for viewing incendiary materialsand the like.

As previously described the left spatial screen of assembly 10 presentsthe near ultraviolet spatial display, and comprises a transparentsubstrate, coated with a phosphor material 13. Many suitable materialsshow visible fluorescence with ultraviolet irradiation. Typicalmaterials include the radium base compounds and organic phosphors.Radium base compounds are preferred for the particular opticalcomponents herein described, ultraviolet sources down to 0.3 micronwavelengths being all that are required in the preferred embodimentsince this lower wavelength allows observation of sources such as thenitrogen ion laser at 0.3371 micron, which is a typical lower wavelengthsource. It should of course be appreciated that if necessary the opticscould be so arranged to permit farther ultraviolet ranges to beobservable. Materials are preferred that will fluoresce at radiations upto wavelengths of at least 0.4 microns, where human vision becomessensitive. Any material with sensitivity tending beyond the 0.4 micronsis also acceptable, since a simple cutoff filter will provide thenecessary isolation. If it is desirable to resolve temporal changes inthe source radiation, the material must additionally have very littlefluorescent persistence, while retaining good quantum efficiency andresolution.

The right hand spatial screen of assembly presents the near infraredspatial display, and like the ultraviolet screen it comprises atransparent substrate coated with a phosphor material 15. Suitablematerials for emitting light when irradiated in the near infrared regioninclude rare-earth doped strontium sulfide, cholesteric liquid crystals,cobalt chloride, and lanthanum fluoride. Of these materials strontiumsulfides doped with rareearths such as europium and samarium arepreferred because of their sensitivity over a wide wavelength band.

Near infrared sensing is more difficult to accomplish than sensingultraviolet. This is because ultraviolet photons have excess energy whencompared to the energy of the visible phosphor photons which aredislodged. In contrast, to get a visible region yield from infraredenergy requires additional energy from an outside source. This isusually accomplished by either amplifying an electronic signal fromvidicons and discrete detectors, or by accelerating electrons betweenthe target and the phosphor surface of an image convertor. The presentinvention substitutes fluorescent material for complex image convertorsand detector arrays, by means of a simple technique of supplementing theinfrared energy by activating the fluorescent material to excited energylevels with blue region light in the 0.4 to 0.55 micron wavelengthregion. This excited energy level of the phosphor coating causes visiblephotons to be dislodged and the phosphor thereby to emit visible lightimmediately upon receiving any near infrared light. The visible emissionpeaks in the orange at approximately 0.64 micron wavelength. Theemissionpersists for the duration of irradiation if periodic reactivation withblue light is supplied, and when the infrared irradiation is removedtheimage disappears in nanoseconds,

facilitating counting of very fast pulse repetition rates of incominglaser light sources.

The blue light activation of the infrared phosphor is accomplished byusing a portable strobe light 17 of the type conventionally used forflash photography,

wherein a spectral filter is placed over the strobe light to limit thetransmission to the blue region. This blue light is concentrated ontothe phosphor screens when triggered by the operator. To protect theoperators eye during the brief, but very intense, flash from the strobelight, an eyepiece blocking shutter 50 is utilized. The blocking shutter50 is actuated when the operator triggers the strobe light.

The eyepiece 30 accommodates the full field of screen assembly 10, andspectral screen 11, with operator comfort. Included as a safetyprecaution in the eyepiece 30 is a strong spectral filter 29 that passesonly the visible energyjemitted from the screens so that any ultravioletor infrared radiation that might pass through their respective phosphorscreens is absorbed before reaching the operator's eye.

Referring now to FIG. 3 it will be observed that collecting optics 1comprises the primary objective mirror 14, the secondary mirror 16, andthe secondary objective lens 18 as previously shown in FIG. 2. FIG. 3 isan optical schematic, illustrating the spectral optics 3 in detail.These spectral optics lie in. an oblique plane located below the imagingoptics 2, as shown in FIG. 4. A light pipe 32 is disposed within thespectroscope, passing through a hole in the secondary objective lens 18,to probe a small portion of the image at point 31, in the focal planeformed by the collecting optics. Light falling on the end of the lightpipe is routed to a location out of the imaging optics path in a mannerwhich prevents interfering with the image formation at screen assembly10. Any suitable optical relay train may be used in the light pipe. Ofthese a bundle of fiber optics is preferred because of low cost, lightweight, and they require no critical adjustment of components toaccommodate curved transmissions. It should be noted that the lightfalling on the light pipe 32 at point 31 and thereafter routed out ofthe imaging'optics produces,

blyl0 and as previously described the opaque spot 12 I may be disposedat any desired location on the screens as a function of the location ofpoint 31 in the focal.

plane. It should'be further noted that only when the opaque spot 12 onone of the three screensis placed over the light source will the lightfrom the source be directed to the light pipe 32 and displayed on thespectral screen 11.

Light emerging from'the output end of the lightpipe 32 is collimated bylens 34, FIG. 3, and directed into a series of mirrors 36, 40 and 44,located at to the collimation axis. The first mirror 36 is a dichroicbeam splitter that reflects light below 0.4 microns andtransmits lightabove that wavelength. The second mirror 40 is a dichroic beam splitterthat reflects visible light and transmits the infrared wavelengths. Thethird mirror 44 is a front-surface mirror that reflects the remaininginfrared light. It should be appreciated that the functions of mirrors36 and 40 could be interchanged if desired, wherein the infraredwavelength would be the first re flected and all light below thatwavelength would be transmitted, and thereafter the last light reflectedwould be the ultraviolet wavelength. Further, it should be clear that ifthe range of wavelengths of interestis sufficiently small then only onemirror and set of associated optics hereinafter described would berequired. Aligned optically with each of the three 45 mirrors 36, 40 and44 are three reflective diffraction gratings 37, 41 and 45 respectively,each having the line spacing and appropriate angular orientation todisperse light in an appropriate manner to their respective spectrumforming lens 38, 42, and 46 and thereby focus across the wavelengthscreen 11. Thus it can be seen that a beam of light emerging from theoutput end of light pipe 32 is subjected to dispersion, and then broughtto focus so that the component waves are arranged in the order of theirwave length in a series of images, or a single image on the spectralscreen 11. As was previously described these images may appear as brightspots or continua, depending on the energy source, at the positionsalong the wavelength scale of screen 11 corresponding to the radiationwavelength. In those instances where the spot is too large or wherecontinua is so broad that the desired resolution is not obtained, thelight beam is stopped-down by aperture wheel 33,

which contains a plurality of various sized apertures that may beselectively placed between the output end of light pipe 32 andcollimating lens 34.

Because of the dispersion of light previously described, the netirradiance on the phosphors for any broadband source is considerablyless than that obtained with the imaging optics 2, of FIG. 2, whereinall wavelengths are effectively focused to the same spot. This is thereason for utilizing dichroic mirrors for the spectral optics, so thatas much light as possible is conserved, and why in the imaging optics,where effective irradiance is higher, the light is simply dividedapproximately in thirds with front-surface mirrors and thereafterfiltered with a resultant greater loss of efficiency. The screen 11 iscoated with the same or similar phosphors utilized for the spatialscreens. The length of the screen 11 from 0.3 microns to 0.4 microns iscoated with one of the ultraviolet sensitive phosphors 13, from 0.4 to0.8 microns comprises ground glass, and from 0.8 to 1.7 microns iscoated with one of the infrared sensitive phosphors 15.

FIG. 4 is a schematic presentation of the combined optical systems ofthe spectroscope when viewed in a side elevation. Collecting optics ltransmit incoming light to secondary objective lens 18 where it entersthe imaging optics 2 and simultaneously transmits light to the front end31 of light pipe 32 where it enters the spectral optics 3 ashereinbefore described.

The construction and operation of the spectroscope will be apparent fromthe foregoing description and it can be clearly seen that the presentinvention is uniquely suited for obtaining image and spectrographic dataon intense sources of light ranging in wavelength from approximately 0.3to 1.7 microns. This range is for illustration purposes, and it shouldbe appreciated that other ranges may be utilized where desirable. Therange of the herein described preferred embodiment of the device isapproximately centered about wavelengths associated with well developedlasers, including neodymium at 1.06 microns, ytterbium at 1.02 microns,and helium-neon at 1.15 microns, and is extended low'enough to includethe nitrogen ion laser at 0.3371 micron. The device is sufficientlysmall to be hand held, weighs less than pounds, and requires onlysufficient battery power for a camera type strobe light to periodicallyactivate the infrared phosphors. Additional features may be added to thedevice if desired, such as source pulse-counting and camera recordingsof the displays. As an example, part of the fiber optics bundle may berouted to a small photomultiplier tube with a mixture of phosphorscreens disposed at its window, so that the pulses can be counted andrates determined with associated circuitry. It will be apparent that theembodiment illustrated is for example only, and that many otherarrangements may be devised to tailor the spectroscope to desiredrequirements, and that the foregoing description is not to be taken as alimitation, the spirit and scope of the invention being limited only bythe claims.

I claim:

1. A spectroscope for simultaneously providing spatial and spectraldisplays of a remote light source comprising:

a plurality of viewing screens;

a collecting optical system for receiving light from a remote source andfocusing the light to a focal plane;

a spatial imaging optical system for receiving a first portion of lightfrom said focal plane for filtering and focusing said first portion oflight into a spatial image on at least one of said viewing screens; and

a spectral optical system for receiving a second portion of light fromsaid focal plane for dispersing and subsequently focusing said secondportion of light so that component waves are arranged in the order oftheir wavelengths in a series of spectral images on at least one of saidviewing screens.

2. The spectroscope of claim 1 wherein the spatial imaging opticalsystem comprises:

a secondary objective lens for collecting said first portion of lightfrom said focal plane;

an image forming lens in optical alignment with said secondary objectivelens for focusing said first portion of light onto one of said viewingscreens; and

a pass-filter adjacent to said image forming lens.

3. The spectroscope of claim 2 wherein said passfilter includesfiltering means for transmitting only infrared light.

4. The spectroscope of claim 2 wherein said passfilter includesfiltering means-for transmitting only ultraviolet light.

5. The spectroscope of claim 2 wherein said passfilter includesfiltering means for transmitting only visible light.

6. The spectroscope of claim 5 further comprising:

a pair of front-surface mirrors disposed between said secondaryobjective lens and said image forming lens for diverting a first portionof the image beam transmitted by said'secondary objective lens away fromsaid image forming lens;

a second image forming lens in optical alignment with said pair offront-surface mirrors for receiving reflected light therefrom andfocusing said light on one of said viewing screens; and

a second pass-filter adjacent to said second image forming lens.

7. The spectroscope of claim 6 wherein said second pass-filter includesfiltering means for transmitting only infrared light.

8. The spectroscope of claim 1 wherein the spectral optical systemcomprises:

a light pipe for routing said second portion of light from said focalplane away from said focal plane;

a collimating lens located at the exit end of said light pipe;

a mirror disposed along the axis of said collimating lens;

a reflective diffracting grating located in optical alignment to receivereflected light from said mirror and reflect dispersed light therefrom;and

a spectrum forming lens located in optical alignment with saidreflective diffracting grating to receive the dispersed light therefromand focus said spectral images on at least one of said viewing screens.

9. The spectroscope of claim 8 wherein said mirror is a dichroic beamsplitter for reflecting only ultraviolet light.

10. The spectroscope of claim 8 wherein said mirror is a dichroic beamsplitter for reflecting only visible light.

11. The spectroscope of claim 8 wherein said mirror is a dichroic beamsplitter'for reflecting only infrared light.

12. The spectroscope of claim 8 wherein said mirror is a first dichroicbeam splitter, and further comprising:

a second dichroic beam splitter disposed along the axis of saidcollimating lens for reflecting visible light and transmitting otherwavelengths;

a second reflective diffracting grating disposed in optical alignment toreceive the visible light reflected from said second dichroic beamsplitter and reflect dispersed light therefrom; and

a second spectrum forming lens located in optical alignment with saidsecond reflective diffracting grating to receive the dispersed lighttherefrom and focus said spectral images on at least one of said viewingscreens.

13. The spectroscope of claim 12 wherein said first dichroic beamsplitter is constructed for reflecting infrared light and transmittinglower wavelengths.

14. The spectroscope of claim 6 wherein said second pass-filter includesfiltering means for transmitting only ultraviolet light.

15. The spectroscope of claim 12 wherein said first dichroic beamsplitter is constructed for reflecting ultraviolet light andtransmitting higher wavelengths.

16. The spectroscope of claim 14 further comprising:

a second pair of front-surface mirrors disposed between said secondaryobjective lens and said image forming lens for diverting a secondportion of the image beam transmitted by said secondary objective lensaway from said image forming lens;

a third image forming lens in optical alignment with said second pair offront-surface mirrors for receiving reflected light therefrom andfocusing said light on one of said viewing screens; and

a third pass-filter adjacent to said third image forming lens fortransmitting only infrared light.

17. The spectroscope of claim 15 further comprising:

a third dichroic beam splitter disposed along the axis of saidcollimating lens for reflecting infrared light and transmitting lowerwavelengths;

a third reflective diffracting grating disposed in optical alignment toreceive the infrared light reflected from said third dichroic beamsplitter and reflect dispersed light therefrom; and

a third spectrum forming lens located in optical alignment with saidthird reflective diffracting grating to receive the dispersed lighttherefrom.

18. A spectroscope for simultaneously providing spa-- tial and spectraldisplays of a light source comprising:

a collecting optical system for receiving light from a remote source andfocusing the light to a focal plane;

a spatial imaging optical system for receiving a first portion of lightfrom said focal plane comprising; an objective lens located adjacent tosaid focal plane,

means for dividing light transmitted through said objective lens intothree light beams,

a spatial screen having a first area sensitive to ultraviolet light, asecond area sensitive to visible light, and a third area sensitive toinfrared light,

an ultraviolet pass-filter disposed in the first light beam for passingultraviolet light to said first screen area,

a visible pass-filter disposed in the second light beam for passingvisible light to said second screen area,

an infrared pass-fllter disposed in the third light beam for passinginfrared light to said. third screen area, a spectral optical system forreceiving a second por- 5 tion of light from said focal planecomprising;

a light pipe for routing said second portion of light away from saidfocal plane, light dispersion means for receiving light from the exitend of said light pipe and dispersing light so that the component wavesare arranged in the order of their wave lengths, and a spectral screenspaced from said light dispersion means for receiving and displaying thedispersed light transmitted thereon.

19. The spectroscope of claim 18 wherein the collecting optical systemcomprises:

a primary objective mirror for collecting incoming light and reflectingthe light in a converging path, said primary objective mirror having ahole located therein;

a secondary objective mirror located in front of said primary mirror forreflecting light from said primary mirror back through said hole in saidprimary 2 mirror; and

wherein said objective lens in the spatial imaging optical system islocated within said hole of said primary objective mirror. v

20. The spectroscope of claim 16 wherein said light dispersion means inthe spectral optical system comprises:

a collimating lens;

a plurality of dichroic beam splitters disposed along the collimationaxis of said collimating lens;

a plurality of reflective diffraction gratings disposed in opticalalignment with said! dichroic beam splitters; and i a plurality ofspectrum forming lenses located in opti cal alignment with said gratingsto focus light therefrom.

21. The spectroscope of claim 18, in the spatial imagingoptical system,wherein said means for dividing light transmitted through, saidobjective lens'into three light beams comprises:

a first mirror located in and intercepting a portion of the opticallight path from said objective lens;

a second mirror located in and intercepting a portion of the opticallight path from said objective lens;

a first image forming lens located in and receiving a portion of theoptical light path from said objective lens;

a third mirror located in optical alignment with said first mirror forreceiving and reflecting light therefrom;

a fourth mirror located in optical alignment with said second mirror forreceiving and reflecting light therefrom;

a second image forming lens located in optical alignment with said thirdmirror; and

a third image forming lens located in optical align ment with saidfourth mirror.

22. A spectroscope for simultaneously providing spa tial and spectraldisplay of a light source comprising:

a collecting optical system for receiving light from a remote source andfocusing the light to a focal plane;

a spatial imaging optical system comprising;

an objective lens located adjacent to said focal plane,

a first image forming lens spaced from and in optical alignment withsaid objective lens,

a visible range pass-filter located adjacent to said image forming lensfor filtering light transmitted from said objective lens through saidfirst imageforming lens,

a screen spaced from said first image forming lens for receiving thevisible image,

means for relaying a portion of light passing through said objectivelens away from said first image forming lens,

a second image forming lens located in optical alignment with saidrelaying means;

an ultraviolet range pass-filter located adjacent to said second imageforming lens for filtering the light transmitted through said secondimage forming lens,

an ultraviolet sensitive screen spaced from said second image forminglens for displaying the ultravi olet image transmitted thereto,

a third image forming lens located in optical alignment with saidrelaying means;

an infrared range pass-filter located adjacent to said third imageforming lens for filtering the light transmitted through said thirdimage form ing lens,

an infrared sensitive screen spaced from said third image forming lensfor displaying the infrared image transmitted thereto,

a spectral optical system comprising;

a light pipe having one end located in said focal plane for directinglight falling thereon to a location outside the light path passingthrough said objective lens in the spatial imaging optical system,

a collimating lens located at the output end of said light pipe,

a plurality of beam splitters for dividing light passing through saidcollimating lens into beams of ultraviolet, visual, and infrared light,

a plurality of reflective diffraction gratings in optical alignment withsaid beam splitters for dispersing said light beams over a spectralfocal plane, and

a spectral screen spaced from said gratings and lying within saidspectral focal plane for displaying the dispersed light transmittedthereto. l t

1. A spectroscope for simultaneously providing spatial and spectraldisplays of a remote light source comprising: a plurality of viewingscreens; a collecting optical system for receiving light from a remotesource and focusing the light to a focal plane; a spatial imagingoptical system for receiving a first portion of light from said focalplane for filtering and focusing said first portion of light into aspatial image on at least one of said viewing screens; and a spectraloptical system for receiving a second portion of light from said focalplane for dispersing and subsequently focusing said second portion oflight so that component waves are arranged in the order of theirwavelengths in a series of spectral images on at least one of saidviewing screens.
 2. The spectroscope of claim 1 wherein the spatialimaging optical system comprises: a secondary objective lens forcollecting said first portion of light from said focal plane; an imageforming lens in optical alignment with said secondary objective lens forfocusing said first portion of light onto one of said viewing screens;and a pass-filter adjacent to said image forming lens.
 3. Thespectroscope of claim 2 wherein said pass-filter includes filteringmeans for transmitting only infrared light.
 4. The spectroscope of claim2 wherein said pass-filter includes filtering means for transmittingonly ultraviolet light.
 5. The spectroscope of claim 2 wherein saidpass-filter includes filtering means for transmitting only visiblelight.
 6. The spectroscope of claim 5 further comprising: a pair offront-surface mirrors disposed between said secondary objective lens andsaid image forming lens for diverting a first portion of the image beamtransmitted by said secondary objective lens away from said imageforming lens; a second image forming lens in optical alignment with saidpair of front-surface mirrors for receiving reflected light therefromand focusing said light on one of said viewing screens; and a secondpass-filter adjacent to said second image forming lens.
 7. Thespectroscope of claim 6 wherein said second pass-filter includesfiltering means for transmitting only infrared light.
 8. Thespectroscope of claim 1 wherein the spectral optical system comprises: alight pipe for routing said second portion of light from said focalplane away from said focal plane; a collimating lens located at the exitend of said light pipe; a mirror disposed along the axis of saidcollimating lens; a reflective diffracting grating located in opticalalignment to receive reflected light from said mirror and reflectdispersed light therefrom; and a spectrum forming lens located inoptical alignment with said reflective diffracting grating to receivethe dispersed light therefrom and focus said spectral images on at leastone of said viewing screens.
 9. The spectroscope of claim 8 wherein saidmirror is a dichroic beam splitter for reflecting only ultravioletlight.
 10. The spectroscope of claim 8 wherein said mirror is a dichroicbeam splitter for reflecting only visible light.
 11. The spectroscope ofclaim 8 wherein said mirror is a dichroic beam splitter for reflectingonly infrared light.
 12. The spectroscope of claim 8 wherein said mirroris a first dichroic beam splitter, and further comprising: a seconddichroic beam splitter disposed along the axis of said collimating lensfor reflecting visible light and transmitting other wavelengths; asecond reflective diffracting grating disposed in optical alignment toreceive the visible light reflected from said second dichroic beamsplitter and reflect dispersed light therefrom; and a second spectrumforming lens located in optical alignment with said second reflectivediffracting grating to receive the dispersed light therefrom and focussaid spectral images on at least one of said viewing screens.
 13. Thespectroscope of claim 12 wherein said first dichroic beam splitter isconstructed for reflecting infrared light and transmitting lowerwavelengths.
 14. The spectroscope of claim 6 wherein said secondpass-filter includes filtering means for transmitting only ultravioletlight.
 15. The spectroscope of claim 12 wherein said first dichroic beamsplitter is constructed for reflecting ultraviolet light andtransmitting higher wavelengths.
 16. The spectroscope of claim 14further comprising: a second pair of front-surface mirrors disposedbetween said secondary objective lens and said image forming lens fordiverting a second portion of the image beam transmitted by saidsecondary objective lens away from said image forming lens; a thirdimage forming lens in optical alignment with said second pair offront-surface mirrors for receiving reflected light therefrom andfocusing said light on one of said viewing screens; and a thirdpass-filter adjacent to said third image forming lens for transmittingonly infrared light.
 17. The spectroscope of claim 15 furthercomprising: a third dichroic beam splitter disposed along the axis ofsaid collimating lens for reflecting infrared light and transmittinglower wavelengths; a third reflective diffracting grating disposed inoptical alignment to receive the infrared light reflected from saidthird dichroic beam splitter and reflect dispersed light therefrom; anda third spectrum forming lens located in optical alignment with saidthird reflective diffracting grating to receive the dispersed lighttherefrom.
 18. A spectroscope for simultaneously providing spatial andspectral displays of a light source comprising: a collecting opticalsystem for receiving light from a remote source and focusing the lightto a focal plane; a spatial imaging optical system for receiving a firstportion of light from said focal plane comprising; an objective lenslocated adjacent to said focal plane, means for dividing lighttransmitted through said objective lens into three light beams, aspatial screen having a first area sensitive to ultraviolet light, asecond area sensitive to visible light, and a thiRd area sensitive toinfrared light, an ultraviolet pass-filter disposed in the first lightbeam for passing ultraviolet light to said first screen area, a visiblepass-filter disposed in the second light beam for passing visible lightto said second screen area, an infrared pass-filter disposed in thethird light beam for passing infrared light to said third screen area, aspectral optical system for receiving a second portion of light fromsaid focal plane comprising; a light pipe for routing said secondportion of light away from said focal plane, light dispersion means forreceiving light from the exit end of said light pipe and dispersinglight so that the component waves are arranged in the order of theirwave lengths, and a spectral screen spaced from said light dispersionmeans for receiving and displaying the dispersed light transmittedthereon.
 19. The spectroscope of claim 18 wherein the collecting opticalsystem comprises: a primary objective mirror for collecting incominglight and reflecting the light in a converging path, said primaryobjective mirror having a hole located therein; a secondary objectivemirror located in front of said primary mirror for reflecting light fromsaid primary mirror back through said hole in said primary mirror; andwherein said objective lens in the spatial imaging optical system islocated within said hole of said primary objective mirror.
 20. Thespectroscope of claim 16 wherein said light dispersion means in thespectral optical system comprises: a collimating lens; a plurality ofdichroic beam splitters disposed along the collimation axis of saidcollimating lens; a plurality of reflective diffraction gratingsdisposed in optical alignment with said dichroic beam splitters; and aplurality of spectrum forming lenses located in optical alignment withsaid gratings to focus light therefrom.
 21. The spectroscope of claim18, in the spatial imaging optical system, wherein said means fordividing light transmitted through said objective lens into three lightbeams comprises: a first mirror located in and intercepting a portion ofthe optical light path from said objective lens; a second mirror locatedin and intercepting a portion of the optical light path from saidobjective lens; a first image forming lens located in and receiving aportion of the optical light path from said objective lens; a thirdmirror located in optical alignment with said first mirror for receivingand reflecting light therefrom; a fourth mirror located in opticalalignment with said second mirror for receiving and reflecting lighttherefrom; a second image forming lens located in optical alignment withsaid third mirror; and a third image forming lens located in opticalalignment with said fourth mirror.
 22. A spectroscope for simultaneouslyproviding spatial and spectral display of a light source comprising: acollecting optical system for receiving light from a remote source andfocusing the light to a focal plane; a spatial imaging optical systemcomprising; an objective lens located adjacent to said focal plane, afirst image forming lens spaced from and in optical alignment with saidobjective lens, a visible range pass-filter located adjacent to saidimage forming lens for filtering light transmitted from said objectivelens through said first image-forming lens, a screen spaced from saidfirst image forming lens for receiving the visible image, means forrelaying a portion of light passing through said objective lens awayfrom said first image forming lens, a second image forming lens locatedin optical alignment with said relaying means; an ultraviolet rangepass-filter located adjacent to said second image forming lens forfiltering the light transmitted through said second image forming lens,an ultraviolet sensitive screen spaced from said second image forminglens foR displaying the ultraviolet image transmitted thereto, a thirdimage forming lens located in optical alignment with said relayingmeans; an infrared range pass-filter located adjacent to said thirdimage forming lens for filtering the light transmitted through saidthird image forming lens, an infrared sensitive screen spaced from saidthird image forming lens for displaying the infrared image transmittedthereto, a spectral optical system comprising; a light pipe having oneend located in said focal plane for directing light falling thereon to alocation outside the light path passing through said objective lens inthe spatial imaging optical system, a collimating lens located at theoutput end of said light pipe, a plurality of beam splitters fordividing light passing through said collimating lens into beams ofultraviolet, visual, and infrared light, a plurality of reflectivediffraction gratings in optical alignment with said beam splitters fordispersing said light beams over a spectral focal plane, and a spectralscreen spaced from said gratings and lying within said spectral focalplane for displaying the dispersed light transmitted thereto.